During cornering, a motorcycle is banked or leaned toward the inside of the corner at an angle sufficient to enable the weight of the motorcycle to offset the centrifugal force pulling the motorcycle outside toward the outside of the corner. These motions act upon the center of gravity of the whole motorcycle which is acted upon by the offsetting centrifugal force forcing the motorcycle outwardly from the corner and the force of gravity attracting the motorcycle inside due to the inward lean angle of the motorcycle.
For increased cornering speeds, the bank or lean angle of the motorcycle must become larger in order to balance the centrifugal force and the force of gravity. However, the lean angle is limited by several factors related to the construction of the motorcycle. The motorcycle may not be leaned to an angle greater than that which provides ground clearance to prevent portions of the motorcycle including the engine, steps or foot pegs, etc. from scraping the ground. Thus, the limitation of the width of the motorcycle limits the bank angle which may be employed. This bank angle is often limited by engine width. While the engine may be raised in the frame in order to obtain a higher bank angle, raising the motorcycle engine in the frame raises the center of gravity and impairs transient cornering performance due to the consequent higher inertial forces which must be supplied to the motorcycle to initiate a change in attitude.
It is therefore an object of the present invention to provide a motorcycle which can corner at higher rates of speed without encountering the bank angle limitations mentioned above.
It is another object of the present invention to provide a motorcycle with a fixed frame member and a moveable portion of the frame.
It is still another object of the present invention to provide a motorcycle structure which enables a shifting of at least a portion of the motorcycle structure to shift the center of gravity of at least a portion of the motorcycle structure toward the inside of the center of gravity of a fixed portions of the motorcycle to thereby shift the effective total center gravity of the motorcycle to the inside of the corner.
These and other objects of the present invention are achieved by the unique motorcycle construction according to the teachings of the present application.